The counterweights currently used for tensioning the wires of a catenary of a train were traditionally produced as an assembly of smelting pieces, mounted to a rod that tensions the wires forming the catenary.
The need to reduce costs, the rising price of iron and steel and the problem of the same being stolen in some countries make necessary a change in the traditional way of manufacturing these counterweights.
The option currently employed in order to face up to these limitations consists of using counterweights made from mixtures including concrete, which are well known in other sectors.
The main disadvantage of this consists in guaranteeing the durability required of these elements, given that they are exposed to the elements for long periods of time.
It must also be added that, although there don't seem to be any spatial restrictions, practical conditions do come into play as regards the size and shape of said counterweights, particularly of those designed for high speed railway lines, where the circulation of the train may come to exert considerable aerodynamic loads on the counterweights.